Re: [lkcd-devel] Re: What's left over.

[Eric W. Biederman]

Werner Almesberger <[e-mail]> writes:

> Eric W. Biederman wrote:
> > What I was thinking is that the process would for and exec
> > something like "/etc/rc 6" or maybe "/etc/rc 7" to be clean.
> > And that script would do all of the user space shutdown.
> 
> Yes, but init also does a kill(-1,...) to get rid of all processes,
> before the last steps of system shutdown. So you have to somehow
> make your "page holding" process survive beyond this point.

True.  But it is just as easy to drop the file into something like
ramfs.  Or a file on the read only file on the root filesystem.  Now
that we can having shutdown do a pivot_root and totally unmounting
the root filesystem is probably a good idea.

> > My feel is that kexec-on-panic is a rather different problem.
> 
> You make it a different problem by assuming that you'd have a
> kernel that is specifically built for running at a "safe"
> location.  

Well at least the part cleans up after the running kernel.  That is
what I think it takes to make it stable.  Perhaps I am wrong, but
I think getting other architecture stable is very hard.

> If you assume that you're just using your normal
> kernel, the two problems converge again. There are still a
> few things that are different, like the checksumming, but
> they can safely be added at a later time.

I guess I can be proven wrong.

Eric